[Decreasing Susceptibility of MRSA to Daptomycin During the Course of Treatment].

Methicillin-resistant Staphylococcus aureus (MRSA) with decreased susceptibility to daptomycin (DAP) were isolated from 4 patients receiving DAP from November 2013 to May 2014. These patients were treated with DAP for more than 7 days in all the cases. The pulsed-field gel electrophoresis (PFGE) patterns for MRSA isolates recovered from each patient pre- and post-DAP therapy were identical. Sequencing of mprF detected 2 amino acid substitutions (T345I or L826F) in 2 of the isolates. These results suggest that in vivo MRSA was resistant to DAP during DAP therapy. Furthermore, the MICs for DAP can vary by±1 dilution depending on the susceptibility test. When testing DAP susceptibility, there is a need to monitor reproducibility using different susceptibility tests, including the CLSI method.

The efficacy, safety, and pharmacokinetics of biapenem administered thrice daily for the treatment of pneumonia in the elderly.

Biapenem has been widely used to treat bacterial pneumonia; however, there is little information concerning its efficacy and safety in elderly patients. Based on pharmacokinetic-pharmacodynamic theory, administration of biapenem thrice rather than twice daily would be expected to be more effective because of longer time above the minimum inhibitory concentration. In this study, we aimed to evaluate the efficacy, safety, and pharmacokinetics of biapenem (300 mg) administered thrice daily in pneumonic patients aged 65 years or older. Biapenem was effective in 22 of 25 patients, as assessed by the improvement in clinical symptoms and/or the eradication of the causative organisms, and caused no serious adverse events. The pharmacokinetic profile was established based on simulations using a modeling program. Among 17 patients whose causative organisms were detected, time above the minimum inhibitory concentration was estimated to be 100% in 16 patients, all of whom showed clinical improvement. The results of this study confirmed the efficacy and safety of 300 mg of biapenem administered thrice daily for the treatment of pneumonia in elderly patients.

Tetracycline, metronidazole and amoxicillin-metronidazole combinations in proton pump inhibitor-based triple therapies are equally effective as alternative therapies against Helicobacter pylori infection.

BACKGROUND: A proton pump inhibitor (PPI)-based triple therapy with clarithromycin (CAM) and amoxicillin (AMPC) is now a standard regimen for Helicobacter pylori (HP) eradication in Japan. However, the CAM-resistant rate has increased recently and alternative therapies are sorely needed. Therefore the aim of the present study was to evaluate the effectiveness and safety of the PPI-tetracycline (TC)-metronidazole (MNZ) regimen (the PTM regimen) as an alternative therapy in comparison with the PPI-AMPC-MNZ (PAM) regimen. METHODS: Sixty-four HP-positive patients visiting the HP-eradication clinic in Tokai University Hospital from July 1998 to March 2003 were treated with either PTM or PAM as alternative therapies. The HP eradication was assessed by urea breath test (UBT), HP stool antigen test, or HP culture method more than 2 months after completion of the treatments. The drug resistances against CAM, AMPC, TC, and MNZ were assessed by the agar dilution method. RESULTS: Fifty-six patients (26 PTM and 30 PAM) completed medication and evaluation of the eradication. The eradication rates of PTM were 82.8% (24/29) and 92.3% (24/26), while those of PAM were 74.3% (26/35) and 89.7% (26/29) by intention-to-treat and per-protocol analysis, respectively. The differences between the regimens were not statistically significant. There were no severe adverse effects observed in either of the regimens. The drug-resistance analyses showed 15 CAM- and one MNZ-resistant cases but no TC or AMPC resistance in the available 25 samples. CONCLUSION: The PTM and PAM regimens were equally effective and safe as alternative HP eradication therapies. And PTM would be particularly useful in penicillin allergy cases.

The in vitro and in vivo antibacterial characterization of vancomycin and linezolid against vancomycin-susceptible and -resistant enterococci.

The present study was designed to compare in vitro antibacterial activities of linezolid and vancomycin against vancomycin-susceptible Enterococcus faecalis (VSEF) and vancomycin-resistant enterococci (VRE) isolated in Japan with those of quinupristin-dalfopristin, teicoplanin and minocycline, and the in vitro short time bactericidal activity and the in vivo activities of linezolid and vancomycin against vancomycin-susceptible and -resistant E. faecalis. The MIC90s of linezolid, quinupristin-dalfopristin, vancomycin, teicoplanin and minocycline for VSEF and VRE were both 2 mg/L, both 2 mg/L, 2 and >128 mg/L, 0.25 and >128 mg/L, and both 32 mg/L, respectively. The efficacy of linezolid for mice with bacteraemia caused by VSEF was similar to that of vancomycin, but the elimination ratio of viable organisms from the blood of mice treated with vancomycin was significantly higher than in linezolid-treated and untreated mice at 2 h post-administration, and those of the two groups at 4 and 6 h were significantly higher than in untreated mice. Moreover, linezolid was highly active in mice with bacteraemia caused by vancomycin-resistant E. faecalis because this drug had potent in vitro activity against the organisms. Our results indicate that linezolid is suitable for the treatment of VRE and VSEF bacteraemia, and vancomycin is suitable for VSEF bacteraemia.

[Anti-Helicobacter pylori effects of Bainiku-ekisu (concentrate of Japanese apricot juice)].

Helicobacter pylori (H.p.) bacteria are the major causes of gastro-duodenal disease, and some association with stomach cancer has been suggested. Recently, H.p. eradicating treatment has been practiced using antibiotics and proton-pump inhibitors. However, at the same time, some reports have been made on the side-effects of this treatment; allergic reactions and uneffective resistant bacteria. Under these circumstances, there is a strong need for medicines, which are less harmful to the body, can be administered repeatedly, are less expensive, and yet as effective as antibiotics in inhibiting the bacteria, and in fact, some studies have been undertaken in this regard. We placed our focus on Bainiku-ekisu (Concentrate of Japanese apricot juice) which, as a Japanese folk remedy, has been used for the treatment of gastritis and enteritis since ancient times, and studied its bacteriosterile affects. The major ingredients of Bainiku-ekisu are citric acid (32%) and malic acid (11%), while its pH represents strong acid. We measured the bacteriosterile effects of Bainiku-ekisu by culturing ten H.p. strains originating from gastro mucous membrane respectively in a Bainiku-ekisu concentration of 0.156%, 0.313%, 0.625% and 0.9%, and measured the level of MIC (minimum inhibiting concentration of development). As a result, out of ten H.p. strains four of them presented strong bacteriosterile effects in a concentration of less than 0.156%, and six of them, in a concentration of less than 0.313%. Furthermore, in order to measure the bacteriosterile effects against H.p. in the stomach we measured the quantity of bacteria in 0 minutes, five minutes, and ten minutes after mixing ten H.p. strains suspended in physiological salt solution with a Bainiku-ekisu solution of 0.3% and 0.9% dissolved in aseptic physiological salt solution. As a result, within five minutes after mixing, every one of the ten H.p. strains was observed to present strong bacteriosterile effects. These results suggest that Bainiku-ekisu can be considered as a fool likely to prevent the development of H.p. as well as the future possibility of making clinical applications to H.p. infection.

A remarkable reduction in the susceptibility of Neisseria gonorrhoeae isolates to cephems and the selection of antibiotic regimens for the single-dose treatment of gonococcal infection in Japan.

We compared the susceptibilities of 100 Neisseria gonorrhoeae isolates obtained from January to June 2000 to a variety of antimicrobial agents, including various cephems, with the susceptibilities of 55 isolates obtained from May to December 1995. In 11 of the 15 cephems tested, the MIC50 (minimum inhibitory concentration for 50% of isolates) ratios, calculated by dividing the MIC50 for isolates from 2000 by that for isolates from 1995, showed 4-fold to 16-fold differences. The MIC90 ratios of cefodizime and cefditoren showed only a 1-fold and 2-fold difference, respectively. However, the MIC90 ratios of the remaining 13 cephems showed 4-fold to 64-fold differences. We selected the most favorable antibiotic regimens for the single-dose treatment of gonorrhea in Japan according to the antigonococcal activity and pharmacokinetics, based on the criterion (therapeutic time) proposed by Moran and Levine i.e., the regimen should produce a concentration in the serum or plasma at least four times that of the MIC90 value for at least 10 h. Of the 20 single-dose regimens evaluated, only ceftriaxone 1 g intravenously and cefodizime 1 g intravenously were found to have a therapeutic time of more than 10 h for the isolates from 2000. Our results indicated that the susceptibilities of the isolates from 2000 to all the cephems tested, except for cefditoren and cefodizime, decreased remarkably in comparison with the susceptibilities of the isolates from 1995, while parenteral ceftriaxone 1 g and cefodizime 1 g appeared to be the most favorable single-dose regimens for the treatment of gonococcal infections in Japan.